Facing the Germans couldn't have been any worse than facing the Celts.
The initial Roman conquest of Britain took place during the reign of Claudius, and was nearly wrapped up under his successor Nero. Those soldiers were Romans, other Italians, and colonials who’d lived for generations under Roman rule. Other than Boudicca’s revolt (which was ultimately destroyed by a single Roman legion), Rome had no trouble with Britain other than the pretender Carausius, and his short-lived independent empire was one of several that had divided the entire Roman Empire during that period. Finally Rome abandoned the province during the terminal civil wars and invasions. They left their final installations in good order, probably against the possibility of reoccupation.
Roman military administration was typically carried out by troops foreign to the area, and the auxiliaries used for such assignments were chosen based on the need for superior matchups against whatever local battle practices were. So, in Britain, the Romans brought in Sarmatian cavalry, which became available after the Sarmatians themselves were defeated near the Black Sea. As with most (maybe all) empires historically, Rome shuffled subject peoples around via the use of auxiliaries (such as these Sarmatians).
Augustus had disbanded half of the regular legions after the defeat of Antony, retiring the numbers as it were, reducing the regulars to 28 legions (plus the Praetorian Guard, which remained with the Emperor) and created an equal number (28) of auxiliary legions, which varied in size, and had at least somewhat Romanized field command, and observers or liaisons who were (at least) bilingual (or had bi- or multi-lingual slaves).
Fort find adds to potted history of Romans’ boozing
http://www.freerepublic.com/focus/chat/2799508/posts